Sailing With the Sun

light sail   Here is an opportunity to include a picture with the Planetary Society Light Sail mission that is scheduled to be launched on the 20th.
   A light Sail is like sailing on water except that it is done in space using the charged particles of the solar wind. I stand corrected! I have incorrectly described the solar sail and how it was like wind sailing on water. This was pointed out by a NASA JPL Scientist colleague and with his permission I am re-posting his comments below.

“Your brief description of how a light sail works is wrong. TPS’ website reads “LightSail is designed to demonstrate solar sailing, using the momentum of sunlight to propel small spacecraft through space.“ The solar wind has nothing to do with propelling a light sail. There are proposals to harness the solar wind for propulsion but they involve the use of a large-area spanning magnetic field to take advantage of the momentum of the charged particles in the solar wind.
   The first demonstration of the use of the pressure of sunlight in space, that I’m aware of, was by Mariner 10 while it orbited the Sun between its Mercury flybys. To reduce the consumption of attitude control propellant, its solar panels were oriented to reflect sunlight in suitable directions. The mission managed two additional flybys after the initial one planned in the primary mission. Today, the Kepler mission’s K2 extension maintains its orientation for weeks at a time by the orienting its solar panels to use the pressure of sunlight, combined with its two remaining reaction wheels.”

   This link takes you to the Planetary Society web site for more information about sending your selfie. Just be careful if using a selfie stick!!
The link below is to a web site where there is a short Science Fiction story about a solar sailing race around the Earth and Moon.
   The shorty story: The Wind from the Sun by Arthur C. Clarke


Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

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